1. Technical Field
Exemplary embodiments of the present invention relate to slurry compositions for selectively polishing silicon nitride relative to silicon oxide, methods of polishing a silicon nitride layer and methods of manufacturing a semiconductor device using the same. Particularly, exemplary embodiments of the present invention relate to slurry compositions for selectively polishing silicon nitride relative to silicon oxide that may be employed in a semiconductor manufacturing process, methods of polishing a silicon nitride layer and methods of manufacturing a semiconductor device using the same
2. Description of the Related Art
A semiconductor manufacturing process generally includes forming a layer such as an insulation layer or a conductive layer on a substrate, planarizing a surface of the layer, etching the layer to form a pattern having a predetermined shape, or the like.
A process for planarizing a layer may be, for example, an etch-back process, a reflow process, a chemical mechanical polishing (CMP) process or the like. The CMP process is widely used for global planarization or for forming a highly integrated circuit device, as the global planarization may only be achieved by the CMP process and the CMP process has excellent planarization quality.
In the CMP process, a semiconductor wafer to be polished is mounted on a chuck, a slurry composition including an abrasive is provided between the semiconductor wafer and a polishing pad, and then the semiconductor wafer is rotated and pressed against the polishing pad so that the semiconductor wafer is planarized. The semiconductor wafer is mechanically polished by rubbing a surface of the semiconductor wafer with the abrasive and the polishing pad, and also chemically removed by a chemical reaction between chemical components of the slurry composition and the surface of the semiconductor wafer.
The polishing efficiency of the CMP process may be determined by the type of a CMP apparatus, components of the slurry composition, the type of the polishing pad and the like. Among several factors, the components of the slurry composition may have an influence on the polishing efficiency. With regard to the polishing efficiency, the slurry composition should be able to rapidly polish an object, and also should not be able to cause damage to several structures adjacent to the object to be polished.
Commercial slurry compositions have been mainly employed in polishing a silicon oxide layer using a silicon nitride layer as a polishing stop layer, because the slurry compositions exhibit a polishing rate of a silicon oxide layer substantially faster than the polishing rate of a silicon nitride layer. When such slurry compositions are used in polishing a silicon nitride layer, the polishing efficiency may decrease due to a low polishing rate of silicon nitride, and a silicon oxide layer which may be exposed during the polishing process can be unintentionally damaged. Additionally, the slurry compositions may not be expected to have a high quality of planarization and uniformity for a silicon nitride layer, and there also may be difficulty in determining a polishing stop point.